Nucleic acid materials can be used for the therapeutic modulation of gene expression in the form of small interference RNA (siRNA), antisense RNA, and decoy oligodeoxynucleotides (ODN), as well as for the replacement of defective or missing genes by the expression of exogenously introduced genes. However, most nucleic acid therapeutics have not been shown to be applicable for systemic application due to their very short half-life in the bloodstream and inability to cross cell membranes. Because the delivery of nucleic acid therapeutics to disseminated and widespread disease sites such as metastasized tumors and inflamed tissues can only be achieved by systemic administration, the development of efficient delivery systems suitable for systemic application is crucial to the success of nucleic acid-based therapies (Jones et al., 2013; Shim and Kwon, 2012).
A wide variety of methods has been used to facilitate the delivery of nucleic acids to cells in culture or to whole organism, from cationic chemical agents (cationic lipids, liposomes, polymers or peptides) to physical methods (electrotransfer). Cationic lipid and polymer formulations protect the nucleic acid therapeutics against enzymatic degradation as well as facilitate cellular uptake but may cause severe cytotoxicity and/or serum inactivation probably due to their cationic charge (Kedmi et al., 2010).